The present invention relates to an ink jet system printer and, more particularly, to a nozzle cleaning device in an ink jet system printer of the charge amplitude controlling type.
When an ink droplet issuance operation is interrupted in an ink jet system printer, there is a possibility that a small amount of ink liquid attaches to the front surface of a nozzle around the orifice portion thereof. Further, there is a possibility that a small amount of ink liquid may leak out from the orifice of the nozzle because of the thermal contraction of the ink liquid supply system while the ink droplet issuance operation is interrupted. The thus developed ink liquid attaches to the front surface of the nozzle around the orifice portion thereof. The attached ink liquid will have an influence on the droplet formation condition and prevent an accurate printing operation. Moreover, the attached ink liquid may solidify to block the orifice portion of the nozzle.
To prevent the above-mentioned solidification, it has been proposed to cover the orifice portion of the nozzle when the ink droplet issuance operation is not conducted through the use of a suitable cap member. However, the tight covering is not easily conducted. Moreover, the ink liquid attached to the front surface of the nozzle may change its chemical characteristic even though the ink liquid will not solidify. Thus, the conventional system can not ensure a stable droplet formation operation.
Accordingly, an object of the present invention is to provide an ink jet system printer which ensures a stable droplet formation operation.
Another object of the present invention is to provide a nozzle cleaning device for cleaning a front surface of a nozzle in an ink jet system printer of the charge amplitude controlling type.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a nozzle cleaning element such as a liquid absorptive pad contacts with the front surface of the nozzle when the ink droplet formation operation is not conducted. In a preferred form, the nozzle cleaning element is usually located at a standby position away from the front surface of the nozzle in order not to disturb the printing operation. When the main power supply is thrown, the nozzle cleaning element is first shifted to clean the front surface of the nozzle, and then held at the standby position for ensuring an accurate printing operation.